<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
	<title>函数</title>
</head>
<body>
	<script type="text/javascript">	
	// function sum(x){
	// 	num=0;
	// 	for(var i=1;i<=x;i++){
	// 		num = num+i;
	// 	}
	// 	alert(num);
	// }
	// sum(1000);
	// sum(900)

	function sum1(num1=100,num2=200){
		num3 = num1+num2;
		return num3;
	};

	y=200;实参
	res=sum1(y);
	alert(res);
	
	</script>
	
</body>
</html>